* Fixes handling of multiple stream links and invalid stream names.
* Fixes text regex so it handle hash sign the right way.
* Adds tests for these stream link cases.
After adding the ability to add stream links to messages using
the following pattern '#**stream_name**' there was a problem
with rendering this using our markdown engine because '**' means
bold text so that would render just to bold text.
To solve this I had to add regular expression in marked.js to match
that pattern and when it matches I call handleStreamLinks in echo.js
which will correctly render it to HTML.
Fixes#2218.
[tweaked by tabbott to url-encode the stream name in the URL and
adding the missing "#" in the display].
* Escape " as "
* Enable GFM newlines
* Output a linebreak after <br> in the generated markup
(imported from commit c007ec422054f9fc66a810b66aac70f70a2a1952)
paxapy
Igor Tokarev
Mohsen Ibrahim
hackerkid
Alex Wilson
Leo Franchi